Restoring dentate appearance: A literature review for modern complete denture esthetics

Measurement of vertical anterior teeth display and lip position at smiling in Kurdish population. Age and gender-based evaluation

Statement of Problem

As part of the overall facial analysis, smile analysis is an essential component of diagnosis and treatment planning in the esthetic rehabilitation of a patient with missing anterior teeth.

Purpose

The aim of this study was to investigate the effect of age and gender on the amount of maxillary anterior teeth and associated lip position during smiling in the Kurdish population to establish guidelines for rehabilitating edentulous patients.

Material and methods

Video equipment was used to capture images of 80 Kurdish subjects divided into two groups by age and sex: Forty young subjects (20 women and 20 men aged 21-24 years), and another forty old subjects (20 women and 20 men aged 45-65 years). Three frames for each subject were selected: one representing the entire length of maxillary anterior teeth, another the posed smile frame and the third representing the spontaneous widest smile. These images were used to quantify a dentogingival exposure for each anterior tooth on either side using standardized measurement techniques. The Kruskal-Wallis test was used to evaluate and compare differences in teeth and gingival display and the Chi-square test was used to explore the frequency of smile line types (α = 0.05).

Results

There were no significant age or sex differences in the anterior teeth display of posed smile. However, women displayed more maxillary anterior teeth in both age groups. The highest display was for lateral incisors, followed by central incisors and canine (61.3%, 58.9%, and 49.05% in the young group vs 62.05%, 54.5%, and 53.3% in the old group). On the other hand, a significant age difference was observed in dentogingival display of maxillary anterior teeth during a spontaneous smile, including mainly the lateral incisors length with their overlying gingiva (98.5%, 1.46 mm in young vs 92.1%, 0.47 mm in old). Women show insignificant excess gingival display than men. Low smile line (class IV) was the predominant type of smile in posed smiles (60%-62.5%). While the average smile line (class III) was the dominant type of young (52.5%) and the high (class II) of old (40%) in spontaneous smiles.

Conclusions

Age influences the dental and gingival display of anterior teeth in spontaneous smiles but not in posed smiles. Women generally show more gingiva and teeth in all the parameters evaluated than men. The predominant type of smile changed from (class IV) in posed smile to (class III) of young and to (class II) of old subjects in a spontaneous smile. Dental treatments should be individually planned according to age-related dynamic norms.

Benefit of Hyaluronic Acid to Treat Facial Aging in Completely Edentulous Patients

Hyaluronic acid (HA) is widely used in aesthetic medicine for its moisturizing and anti-aging action. This molecule, which is naturally present in the body, has an interesting response to aging, accentuated in totally edentulous patients. While its aesthetic benefits for facial rejuvenation are well-documented, there is a lack of description and investigation on its therapeutic usefulness for edentulous patients. The management of completely edentulous patients is a daily reality in dental practice and requires specific attention. The aesthetic and functional challenge is considerable. The displacement of the bone base, which is often marked, and lack of soft tissue support are sometimes difficult to correct with prosthetic reconstruction. This review aims to present the physiological processes appearing in completely edentulous patients and prosthetic solutions available to recreate oral functions and counteract facial aging. As prosthetic rehabilitations are not fully satisfying for counterbalancing the impression of excessive facial aging, we investigated the applications of HA injection in the perioral area, in order to improve edentulism treatment, and discussed the advantages and disadvantages, compared to other dermal fillers and rejuvenation therapies. Considering the specific situations of edentulous patients, dermal HA injections help to correct uncompensated bone losses and mucous volume losses and appear to be a therapeutically beneficial for treating completely edentulous patients, without the requirement to full rejuvenation therapy.

Water Sorption, Solubility, and Translucency of 3D-Printed Denture Base Resins

This study aimed to evaluate the water sorption, solubility, and translucency of 3D-printed denture base resins (NextDent, FormLabs, and Asiga), compare them to heat-polymerized acrylic denture base resins, and assess their performance under the effects of thermal cycling. A total of 80 acrylic disc specimens were used in the current study, categorized into four groups (n = 10); in one group, the samples were fabricated conventionally with a heat-polymerizing process (control), while the other three groups were fabricated digitally from different 3D-printed reins (NextDent, FormLabs, and Asiga). Specimens were fabricated according to the manufacturers’ recommendations and immersed in distilled water for 48 h at 37 °C. Data on water sorption, solubility, and translucency measurements (T1) were obtained. All the specimens were subjected to 5000 thermal cycles, and then the measures were repeated using the same method (T2). Data analysis was attained via ANOVA and the post hoc Tukey test (α = 0.05). The type of resin significantly affected the values of water sorption, solubility, and translucency (p < 0.001). The water sorption of 3D-printed resins was increased significantly in comparison to control with or without a thermal cycling effect. In terms of solubility, a significant increase in 3D-printed resins before thermocycling was observed; however, after thermocycling, Asiga had a significantly low value compared to the other groups (p < 0.001). Thermal cycling increased the water sorption and solubility of all tested materials. In comparison to control, the translucency of the 3D-printed resins was significantly decreased (p < 0.001). The translucency was significantly decreased per material in terms of the thermal cycling effect (before and after). NextDent showed significantly low translucency values (p < 0.001) compared to the other groups. All 3D-printed resin groups had higher water sorption and solubility and lower translucency values in comparison to the heat-polymerized resin group. Regardless of resin types, thermal cycling adversely affected all tested properties.

Extra-oral assessment of conventional and CAD-CAM complete denture appearance by dental professionals and CRDP wearers: A randomized survey

INTRODUCTION

Complete removable dental prostheses' (CRDPs) appearance may vary between conventional and contemporary CAD-CAM manufacturing techniques.

OBJECTIVES

The aim of this randomized survey was to analyze appreciation of CRDPs, manufactured with different techniques, by dental professionals and elder CRDP wearers.

METHODS

Four participant groups, comprised of undergraduate students (n=10), postgraduate residents (n=10), dental technicians (n=10) and elder CRDP wearers (n=10), evaluated the appearance of maxillary CRDPs manufactured by six different techniques: three conventional methods 1. flask-pack-press (FP), 2. Injection-molded (IM), 3. intrinsically colored natural gingiva finish before injection-molded (NG) and three CAD-CAM methods 4. milled base with bonded prefabricated teeth (M), 5. fully milled including milled teeth (FM) and 6. rapid-prototyped including printed teeth (P). A randomized, blinded survey included 18 pairwise comparative assessments and 12 individual judgements of the CRDPs on general appearance as well as pink and white aspects. Statistical analyses included parametric- and nonparametric tests as well as linear regression models; the level of statistical significance was set at p<.05.

RESULTS

NG was preferred by the professional groups but not by the elder CRDP wearers (p<.05). P was scored lowest by all four participant groups (p<.05). CRDP wearers' ratings were less severe and within a narrower range. The ratings of the two CAD-CAM milled CRDPs (M and FM) were ranked closer to FP and IM); the order of preference was different depending on the participant groups.

CONCLUSIONS

The findings of this study revealed marked differences in the assessment of CRDP appearances between dental professionals and older CRDP wearers.

CLINICAL SIGNIFICANCE

A shared and informed approach to decision making concerning the CRDP appearance might foster denture acceptance and treatment success.

Effect of Food Colorants on Color of Denture Base Acrylic Resins

Background:

Acrylic resin has been successfully used for complete denture fabrication for many years. Color stability is very crucial clinical properties for dental materials, and color change may be an indicator of aging or damaging of materials.

Aim and Objectives:

This study has been designed to determine the color stability of heat cure denture base acrylic resins in commonly consumed solutions causing stains.

Methodology:

Four hundred disc samples of four commercially used heat cure denture base resins (Trevalon®, DPI®, Veracril®, and Pyrax®) were fabricated (100 in each group). These were checked for any change in optical density by immersing them in four different staining solutions (tea, coffee, turmeric, and betel leaf, i.e., paan) and synthetic saliva for 1-month synthetic saliva was taken as control. The denture cleansers were also evaluated for their efficacy determined by their ability to remove the stains caused by the staining solutions.

Results:

It was observed that Trevalon® showed least change in optical density and coffee illustrated the maximum potential for staining the denture base resins and is the most difficult to be removed using a denture cleanser.

Conclusion:

It can be concluded that Trevalon® demonstrated maximum color stability. Among the staining solutions, coffee caused maximum stains.

Translucency of nanoparticle-reinforced PMMA denture base material: An in-vitro comparative study

The aim of this study was to assess the translucency of denture base acrylic resin reinforced with zirconium dioxide (ZrO₂NPs), silicon dioxide (SiO₂NPs), and diamond (DNPs) nanoparticles. A total of 130 heat-polymerized acrylic discs (15×2.5 mm) were fabricated conventionally and divided into control and experimental groups according to nanoparticle type and concentration (0.5, 1, 1.5, and 2.5 wt%). Unmodified acrylic resin specimens served as control. All specimens were thermocycled (5,000 cycles). Translucency was measured using a spectrophotometer. ANOVA and post-hoc Turkeys' test were used for data analysis at α=0.05. The translucency of modified PMMA was significantly lower than control (p<0.05) except 0.5% ZrO₂NPs and SiO₂NPs (p>0.05) which exhibited the highest translucency values among modified groups. As the NPs concentration increased, the translucency decreased and the lowest value was seen with 2.5% DNPs (1.18±0.10). The addition of ZrO₂NPs, SiO₂NPs, and DNPs into denture base resin decreased the translucency.

Tooth Shade Preferences among the General Public

PURPOSE

To identify laypersons' most preferred tooth shade as a function of observer and patient factors, namely patients' skin shade and observers' socio-demographics.

MATERIALS AND METHODS

Two online surveys using computer-designed perioral images with different shades of the skin and teeth were distributed to participants in Montreal (Canada) and San Francisco (USA). The first survey (n = 120) was designed to assess public preferences of tooth shade value, hue and chroma as a function of the skin color of the perioral image (model), and the demographic characteristics of the observer. The first survey included 6 sets of 9 identical perioral images. A different skin shade (from very dark to very light) was used for each set of images, and each set of images presented teeth with different tooth shades which included three different levels of value (2M1, 3M1, 4M1), hue (3L1.5, 3M1, 3R1.5), and chroma (3M1, 3M2, 3M3) of the Vita 3D Master shade guide. Participants were asked to choose their preferred image for each category (value, hue, chroma) within each set of skin shades. A second survey was performed to pinpoint the tooth shade that is preferred the most by the general public. In this survey, images with four tooth shades (1M1, 2M1, 3M1, 4M1) and 6 skin shades were distributed (n = 70). Ordinal logistic regression was used to identify significant predictors of preferred tooth shades.

RESULTS

Most of the participants preferred teeth with the highest value (54%), a neutral hue (59%) and the lowest chroma (89%). About 75% of the participants preferred 1M1 the lightest tooth shade over other shades regardless of their demographics or skin color of the model. Among the observer-related variable, age was the most significant predictor of people preferred tooth shade (p = 0.019).

CONCLUSION

This study showed that there are common preferences in terms of tooth shade value, hue and chroma among participants regardless of demographic variables and facial skin shades. This data could guide dentists for tooth shade selection in the clinical practice.

A Comparison of the Color Stability of Conventional and CAD/CAM Polymethyl Methacrylate Denture Base Materials

Objective

The aim of this study was to evaluate the color stability of a heat polymerized resin, an auto-polymerizing resin, a urethane dimethacrylate resin and a CAD/CAM PMMA block resin stored in different storage media.

Materials and methods

60 disc-shaped specimens (15×2 mm) were fabricated for each group. A total of 240 disc-shaped specimens were thermal-cycled for 5,000 cycles. Then specimens were randomized into 4 groups (n= 15) according to storage media: coffee, coke, red wine and distilled water (control group). The color measurement of each sample was performed using a spectrophotometer before and after storage (after 7 and 30 days), and color changes (ΔE) were calculated.

Results

All the denture base materials demonstrated dissimilar color changes after stored in the different storage media in both evaluation stages. In all storage media, CAD-CAM denture base resins showed the minimum in color change. In all denture base resins, red wine showed a higher degree of color change than coke or coffee.

Conclusion

The color stability of CAD-CAM denture base resins is better than any of the other kind of denture base resins. The color change values of all groups except Eclypse stored in red wine had clinically detectable values.

Flipped clinical training: a structured training method for undergraduates in complete denture prosthesis

PURPOSE

To design and implement flipped clinical training for undergraduate dental students in removable complete denture treatment and predict its effectiveness by comparing the assessment results of students trained by flipped and traditional methods.

METHODS

Flipped training was designed by shifting the learning from clinics to learning center (phase I) and by preserving the practice in clinics (phase II). In phase I, student-faculty interactive session was arranged to recap prior knowledge. This is followed by a display of audio synchronized video demonstration of the procedure in a repeatable way and subsequent display of possible errors that may occur in treatment with guidelines to overcome such errors. In phase II, live demonstration of the procedure was given. Students were asked to treat three patients under instructor's supervision. The summative assessment was conducted by applying the same checklist criterion and rubric scoring used for the traditional method. Assessment results of three batches of students trained by flipped method (study group) and three traditionally trained previous batches (control group) were taken for comparison by chi-square test.

RESULTS

The sum of traditionally trained three batch students who prepared acceptable dentures (score: 2 and 3) and unacceptable dentures (score: 1) was compared with the same of flipped trained three batch students revealed that the number of students who demonstrated competency by preparing acceptable dentures was higher for flipped training (χ²=30.996 with p<0.001).

CONCLUSION

The results reveal the supremacy of flipped training in enhancing students competency and hence recommended for training various clinical procedures.

Perception of Esthetic Impact of Smile Line in Complete Denture Wearers by Different Age Groups

PURPOSE

To evaluate esthetic perceptions based on tooth exposure when smiling of patients wearing complete dentures by evaluators in different age groups.

MATERIALS AND METHODS

Alterations were made to a front view photograph of a smiling patient wearing complete maxillary and mandibular dentures. Alterations in the smile line were simulated to increase or decrease tooth exposure (increments of 0.5 mm). For this purpose, image manipulation software was used. After manipulation, images were printed on photo paper, attached to a questionnaire, and distributed to individuals in three age groups (n = 150). To evaluate the esthetic perception for each image, a visual analog scale was used, with 0 representing least attractive, 5 representing attractive, and 10 representing very attractive. Differences between examiners were analyzed using the Mann-Whitney test. All statistical analyses were performed with a degree of confidence of 95%.

RESULTS

Two evaluators did not observe any differences between images. The images given the best and worst scores were E and O (alterations of 2 and 7 mm), respectively, in the 15- to 19-year-old group, B and O (alterations of 0.5 and 7 mm), respectively, in the 35- to 44-year-old group, and A and M (no alteration and 6 mm alteration), respectively, in the 65- to 74-year-old group. When the images were presented together (images 1 and 2), the unaltered image was selected by individuals of different age groups as the best, and the image with a change of 7 mm was selected as the worst.

CONCLUSION

In this study, complete dental prostheses with smile lines that coincided with the cervical margins of the anterior teeth were the most acceptable. Less exposure of the maxillary teeth when smiling corresponded with decreased attractiveness.

The relationship between innercanthal dimension and interalar width to the intercanine width of maxillary anterior teeth in central Indian population

Statement of Problem:

Selection of proper sized maxillary anterior teeth is one of the difficult clinical steps in complete denture esthetics. Several studies have been reported to establish methods of estimating the combined width of maxillary anterior teeth.

Purpose:

The aim of this study was to determine whether a relationship exists between the innercanthal distance (ICD) and interalar width (IAW) with the combined width of maxillary anterior teeth.

Material and Methods:

The maxillary anterior teeth of 600 adult subjects were examined. ICD was measured between the median angles of the palpebral fissure. IAW was measured between the ala of the nose at their widest point. The mean combined width of the maxillary anterior teeth was determined intraorally at their widest dimension. Pearson's correlation coefficients were calculated to determine the relationship between ICD, IAW and the combined width of maxillary anterior teeth (α =0.05).

Results:

Although the Pearson correlation coefficients were relatively small, a significant relationship existed between innercanthal dimension and IAW (P < 0001).

Conclusion:

Within the limitations of this study, the results suggest that ICD and IAW cannot be used as a preliminary method for determining the width of the maxillary anterior teeth for edentulous patients.

Effect of different solutions on color stability of acrylic resin-based dentures

The aim of this study was to evaluate the effect of thermocycling and immersion in mouthwash or beverage solutions on the color stability of four different acrylic resin-based dentures (Onda Cryl, OC; QC20, QC; Classico, CL; and Lucitone, LU). The factors evaluated were type of acrylic resin, immersion time, and solution (mouthwash or beverage). A total of 224 denture samples were fabricated. For each type of resin, eight samples were immersed in mouthwashes (Plax-Colgate, PC; Listerine, LI; and Oral-B, OB), beverages (coffee, CP; cola, C; and wine, W), and artificial saliva (AS; control). The color change (DE) was evaluated before (baseline) and after thermocycling (T1), and after immersion in solution for 1 h (T2), 3 h (T3), 24 h (T4), 48 h (T5), and 96 h (T6). The CIE Lab system was used to determine the color changes. The thermocycling test was performed for 5000 cycles. Data were submitted to three-way repeated-measures analysis of variance and Tukey's test (p<0.05). When the samples were immersed in each mouthwash, all assessed factors, associated or not, significantly influenced the color change values, except there was no association between the mouthwash and acrylic resin. Similarly, when the samples were immersed in each beverage, all studied factors influenced the color change values. In general, regardless of the solution, LU exhibited the greatest DE values in the period from T1 to T5; and QC presented the greatest DE values at T6. Thus, thermocycling and immersion in the various solutions influenced the color stability of acrylic resins and QC showed the greatest color alteration.

A survey of dentulous and edentulous patient preference among different denture esthetic concepts

STATEMENT OF PROBLEM

Most esthetic preference research and anatomical average analysis come from dentulous populations. If edentulous patients have a different preference, application of this data during denture construction is problematic.

PURPOSE

The aim of this survey was to compare dentulous and edentulous respondent preference among three different denture esthetic concepts.

MATERIAL AND METHODS

A questionnaire and test booklet of standardized full-face digital photographs were used. It included three arrangements during maximum smile for six subjects. Dentulous and edentulous respondents were asked questions about their preference among the three randomly ordered concept photographs for each of the six subjects. A total of 167 dentulous and 269 edentulous questionnaires were analyzed descriptively and with Chi-squared tests to compare the esthetic preference of the respondents.

RESULTS

There was no statistically significant difference overall between dentulous and edentulous preference. Respondent preference varied significantly depending upon subject set and gender. Preference data compared closely to previous research.

CONCLUSION

Within the limitations of this survey, dentulous and edentulous respondent preference among the three esthetic concepts was not significantly different. Questionnaire respondents continued to frequently prefer appearances that are far from the anatomical average.

Virtual implant planning in the edentulous maxilla: criteria for decision making of prosthesis design

OBJECTIVES

To evaluate prosthetic parameters in the edentulous anterior maxilla for decision making between fixed and removable implant prosthesis using virtual planning software.

MATERIAL AND METHODS

CT- or DVT-scans of 43 patients (mean age 62 ± 8 years) with an edentulous maxilla were analyzed with the NobelGuide software. Implants (≥3.5 mm diameter, ≥10 mm length) were virtually placed in the optimal three-dimensional prosthetic position of all maxillary front teeth. Anatomical and prosthetic landmarks, including the cervical crown point (C-Point), the acrylic flange border (F-Point), and the implant-platform buccal-end (I-Point) were defined in each middle section to determine four measuring parameters: (1) acrylic flange height (FLHeight), (2) mucosal coverage (MucCov), (3) crown-Implant distance (CID) and (4) buccal prosthesis profile (ProsthProfile). Based on these parameters, all patients were assigned to one of three classes: (A) MucCov ≤ 0 mm and ProsthProfile≥45(0) allowing for fixed prosthesis, (B) MucCov = 0-5 mm and/or ProsthProfile = 30(0) -45(0) probably allowing for fixed prosthesis, and (C) MucCov ≥ 5 mm and/or ProsthProfile ≤ 30(0) where removable prosthesis is favorable. Statistical analyses included descriptive methods and non-parametric tests.

RESULTS

Mean values were for FLHeight 10.0 mm, MucCov 5.6 mm, CID 7.4 mm, and ProsthProfile 39.1(0) . Seventy percent of patients fulfilled class C criteria (removable), 21% class B (probably fixed), and 2% class A (fixed), while in 7% (three patients) bone volume was insufficient for implant planning.

CONCLUSIONS

The proposed classification and virtual planning procedure simplify the decision-making process regarding type of prosthesis and increase predictability of esthetic treatment outcomes. It was demonstrated that in the majority of cases, the space between the prosthetic crown and implant platform had to be filled with prosthetic materials.

Gingival zenith and its role in redefining esthetics: A clinical study

BACKGROUND

The purpose of this study was to quantify some clinical parameters useful as esthetic guidelines when gingival contour is modified and to compare the left and right sides of six maxillary anterior teeth.

MATERIALS AND METHODS

Maxillary casts mounted on an articulator according to the axis orbital plane were photographed from 35 young adults. The angle formed between the gingival line and maxillary midline (GLA) and the distance between the gingival zenith of the lateral incisor and the gingival line were measured (LID) using a flexible protractor and digital vernier caliper, respectively. The asymmetry was evaluated using a paired t test for the left vs right measurements of GLA and LID. The descriptive statistics for GLA and LID were calculated.

RESULTS

The GLA measurements of the left side (86.7°±4.2°) were significantly greater than those of the right side (84.6°±5.4°), and the mean absolute symmetry for GLA was 1.7°±4.4°. The mean LID measurement was 0.92΁0.11.

CONCLUSIONS

The gingival zenith of the canine is apical to the gingival zenith of the incisors (GLA <90°) and the gingival zenith of the lateral incisor is below or on (17%) the gingival line when head is oriented on the axis orbital plane. A directional asymmetry was shown with the right side higher than the left side. Along with the other parameters related to dental esthetics, these clinical parameters may serve as esthetic guidelines and may enable us to obtain a more predictable outcome.

Use of a Synthetic Bone Substitute to Retard Molariform Tooth Drift After Maxillary Tooth Loss in Ponies

OBJECTIVE

To evaluate the effect of alveolar bone substitute on post-extraction drift of maxillary cheek teeth in ponies.

STUDY DESIGN

In vivo longitudinal experimental study.

ANIMALS

Five ponies (5-7 years) with a healthy dentition.

METHODS

Both maxillary 4th premolar teeth (Triadan 08) were surgically removed. One alveolus was filled with a biocompatible non-resorbable bone substitute (Bioplant 24), whereas the other healed by second intention. A polyvinylsiloxane plug and spring wire isolated the bone substitute from the oral environment. Pathologic changes to dentition and adjacent soft tissue were recorded. Tooth drift was calculated after 1 and 2 years.

RESULTS

At 1 month, bone substitute material was incorporated into healthy tissue. Tooth drift was observed but differed significantly between control and treated sides at 2 years (P<.01). For both techniques, tooth drift differed significantly between years 1 and 2 (P<.001). Total drift in control arcades for year 1 was 10.69+/-2.12 mm and for year 2 was 9.08+/-0.87 mm, whereas for bone substitute arcades it was 9.90+/-1.60 mm for year 1 and 5.60+/-1.78 mm for year 2.

CONCLUSIONS

Partial tooth replacement therapy after maxillary P4 extraction provided good healing in the immediate post-surgical phase. Alveolar filling with bone substitute material significantly slowed post-extraction tooth drift but did not stop it completely. Clinical Relevance- Important changes occur in equine dentition after maxillary cheek teeth removal. Further longer term observations are needed to fully validate study findings.